Co-transesterification of waste cooking oil, algal oil and dimethyl carbonate over sustainable nanoparticle catalysts

Fanghua Li; Max J Hülsey; Ning Yan; Yanjun Dai; Chi-Hwa Wang

doi:10.1016/j.cej.2020.127036

Co-transesterification of waste cooking oil, algal oil and dimethyl carbonate over sustainable nanoparticle catalysts

Chem Eng J. 2021 Feb 1:405:127036. doi: 10.1016/j.cej.2020.127036. Epub 2020 Sep 17.

Authors

Fanghua Li^{1

2}, Max J Hülsey², Ning Yan², Yanjun Dai³, Chi-Hwa Wang^{1

2}

Affiliations

¹ NUS Environmental Research Institute, National University of Singapore, Singapore 138602, Singapore.
² Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117585, Singapore.
³ School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.

Abstract

Key challenges for the application of biodiesel include their high acid value, high viscosity, and low ester content. It is essential to develop later-generation biodiesel from unexploited non-food resources for a more sustainable future. Reuse of biowaste is critically important to address these issues of food safety and sustainability. Thus, the co-transesterification of waste cooking oil (WCO), algal oil (AO) and dimethyl carbonate (DMC) for the synthesis of fatty acid methyl esters (FAMEs) was investigated over a series of nanoparticle catalysts containing calcium, magnesium, potassium or nickel under mild reaction conditions. Nanoparticle catalyst samples were prepared from biowaste sources of chicken manure (CM), water hyacinth (WH) and algal bloom (AB), and characterized using XRD, Raman and FESEM techniques for the heterogeneous production of biodiesel. The catalyst was initially prepared by calcination at 850 °C for 4 h in a major presence of Ca_xMg_yCO₃, KCl and K₂CO₃. The WCO and AO co-conversion of 98% and FAMEs co-selectivity of 95% were obtained over CM nanoparticle catalyst under the reaction conditions of 80 °C, 20 mins and DMC to oil molar ratio of 6:1 with 3% catalyst loading and 3% methanol addition. Under the optimum condition, the density, viscosity, and cetane number of the biodiesel were in the range of diesel standards. Nanoparticle catalysts have been proven as a promising sustainable material in the catalytic transesterification of WCO and AO with the major presence of calcium, magnesium and potassium. This study highlights a sustainable approach via biowaste utilization for the enhancement of biodiesel quality with high ester content, low acid value, high cetane number, and low viscosity.

Keywords: Co-transesterification; Dimethyl carbonate; Nanoparticle catalyst; Non-food bioresources; Waste to energy and resource.